A post-mix beverage dispenser reconstitutes a syrup by mixing it with potable water in pre-settable proportions, and dispenses on demand a beverage, such as orange juice or fruit punch. Typical post-mix dispensers, such as that shown in Reissue U.S. Pat. No. 33,943, have at least one container which holds the syrup. The containers are kept in an enclosed concentrate storage area which is kept cool by a refrigerant-based refrigeration system. The potable water is chilled prior to being mixed by flowing through a potable water coil is submerged in an ice bath tank. Because the concentrate and potable water are cooled, the reconstituted beverage is cool and refreshing.
In the typical dispenser, the same vapor compression refrigeration cycle cools both the ice bath tank and the concentrate storage area. The ice bath tank is filled with bath water which is cooled by a refrigerant coil disposed in the tank. The tank is located in an upper portion of the dispenser behind the concentrate storage area. The refrigerant coil disposed in the ice bath tank is the evaporator component in the refrigeration cycle and ice forms in the tank around the refrigerant coil during the operation of the dispenser.
The concentrate storage area which surrounds the concentrate container is primarily cooled by convection. A fin tubular coil is disposed in the concentrate storage area and is connected in series with the refrigerant coil in the ice bath. Thus, when the refrigerant cycle is energized to supply refrigerant to cool the ice bath, it also cools the concentrate storage area. A fan continuously circulates air over the coil in the concentrate storage area to enhance the cooling effect of the coil. The concentrate storage area is also cooled by heat transfer at an uninsulated common wall between the ice bath and the concentrate storage area.
The ice bath water is constantly agitated by an agitator assembly that has an impeller connected to a shaft that extends downward into the ice bath tank. The shaft is coupled to a motor mounted above the ice bath tank. The motor operates continuously while the dispenser is energized. The impeller agitates the ice bath water at the center of the tank to create turbulence in the bath water.
The temperature in the concentrate storage area is largely dependent on the refrigeration cycle. When the refrigerant is not flowing through the fin-tubular coils, the temperature of the concentrate storage compartment rises to about 42.degree. F. to 44.degree. F. When refrigeration cycle is "on" an refrigerant flows through the coils, the temperature in the concentrate storage area is decreased. Immediately before the end of the on cycle, the compartment could be as low as 34.degree. F. As a result, there is a fluctuation of up to about 10.degree. F. in temperature in the concentrate storage area.